Add intention to replace snake-case test function name with a space-separated

#KT-27143 Fixed

idea/testData/intentions/convertSnakeCaseTestFunctionToSpaced/.intention

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.intentions.ConvertSnakeCaseTestFunctionToSpacedIntention

idea/testData/intentions/convertSnakeCaseTestFunctionToSpaced/camel.kt

@@ -0,0 +1,8 @@
+// CONFIGURE_LIBRARY: JUnit@lib/junit-4.12.jar
+// IS_APPLICABLE: false
+
+import org.junit.Test
+
+class A {
+    @Test fun <caret>testTwoPlusTwoEqualsFour() {}
+}

idea/testData/intentions/convertSnakeCaseTestFunctionToSpaced/snake.kt

@@ -0,0 +1,10 @@
+// CONFIGURE_LIBRARY: JUnit@lib/junit-4.12.jar
+import org.junit.Test
+
+class A {
+    @Test fun <caret>test_two_plus_two_equals_four() {}
+}
+
+fun test() {
+    A().test_two_plus_two_equals_four()
+}

idea/testData/intentions/convertSnakeCaseTestFunctionToSpaced/snake.kt.after

@@ -0,0 +1,10 @@
+// CONFIGURE_LIBRARY: JUnit@lib/junit-4.12.jar
+import org.junit.Test
+
+class A {
+    @Test fun `test two plus two equals four`() {}
+}
+
+fun test() {
+    A().`test two plus two equals four`()
+}